Mark Deeble and Victoria Stone met at a diving class when they were students. Then, after graduation, they worked on an environmental-impact assessment project in the beautiful Fal estuary in Cornwall, southwest England, where a new port was being planned. It was the love of the sea and nature they developed then that led them into the world of wildlife filmmaking, where now they have few peers.

Indeed, their latest film, "Mzima: Haunt of the Riverhorse," about hippos living in the Mzima Springs in Kenya's Tsavo National Park, has picked up no fewer than 40 prizes worldwide, including honors from the hugely prestigious Jackson Hole Wildlife Film Festival (in 2001) and last year's Wild Screen Festival.

Such accolades have, however, been hard won, as the couple explained recently while visiting Tokyo for the first time to learn new shooting and editing techniques for high-definition television being developed by NHK.

After that project in the Fal estuary, the pair explain, they were involved in freelance projects for almost three years, all filmed underwater. However, they found that working with big teams, and moving quickly from one location to another, didn't allow them time to get to know the animals well enough to produce truly original footage.

Fortunately for them, at that time the acclaimed wildlife filmmaker Alan Root was looking for people to work on his "Serengeti" series. Deeble and Stone decided to go to East Africa with him. As Stone says, "Root's approach to filming has always been to be in one place for a long time. So when he asked us to go to Africa, it fitted perfectly with what we wanted to do, which was to really have time to understand what you are making the film about.

"And I think to this day, that approach is what is distinctive about our work."

For Deeble and Stone, now both in their early 40s, that was to be the start of 14 years spent mainly living in the African bush -- 14 years in which they have filmed the biggest and the smallest, from three-ton elephants to insects 2 mm long . . . as well as becoming the parents of two sons who have spent almost their entire lives there.

A typical project takes Deeble and Stone about two years of fieldwork or, for a marine subject, nearly 1,000 hours spent underwater. "Out of those 1,000 hours," Stone explains, "we only generate 30 to 40 hours of film. Mostly, we're waiting and watching, trying to understand what's going on. We always find when we go into the field, it takes us about six months in a new area to see beyond the obvious."

When they were shooting "Mzima" in Kenya, for instance, they became the first to succeed in shooting hippos underwater in detail, which they did by setting up a remote camera on the bed of the pool and changing its position every few days. In this way, they discovered that when hippos are really relaxed, they open their mouths and let fish clean their teeth, or even clean their wounds.

After so long living in the middle of nature, though, the family has found coming home involves a heavy dose of reverse-culture shock. "When I am in the bush," Stone explains, "I am completely open. I relate to every single thing around me. I am letting everything in, because it is not overstimulating. It is easy to take it all in. But in a big city, I have to completely close down, because otherwise, it is too much."

In short, Stone says, she feels that in Africa, despite all the inconveniences, she is "in the right place" -- somewhere she feels "natural with humility." In the bush, she says, their little boys also understood this debt to nature, and knew that "the world out there is much bigger than them."

It's a feeling they will all soon be able to experience again, as their next project is to be about a fig tree in the savannah and the life going on around it. Working with NHK as an official co-producer, Deeble and Stone will this time have the benefit of the remarkable HD technology the company has been researching since 1964, and in which it is considered to be the world leader.

Commenting on the film-makers' style, Masaru Ikeo, their executive producer at NHK, said: "What makes them distinctive is in their choice of the theme. Especially in the United States, big mammals like elephants or lions are popular, but [Deeble and Stone] tend to choose plain and quiet themes that show 'the fragile coexistence of lives.' "

Or, as Stone put it: "If you want to be a wildlife filmmaker, you have to be 100 percent committed to it. It is not easy to get there in the first place, or to stay there. You have to be focused and naturally driven by it.

"I don't think like, 'Oh, I have to go to earn some money,' I go because my soul has to do it."